In mobile communication networks, there is always a challenge to obtain good performance and capacity for a given communications protocol, its parameters and the physical environment in which the mobile communication network is deployed. The evolution of the Universal Mobile Telecommunications Standard Long Term Evolution (UMTS LTE) standard for mobile communications continues with new features to increase the overall capacity and to increase the general performance of the communications network.
The 3GPP TS 36.211 specification entitled “LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation” defines antenna ports for the downlink (i.e. for transmission from a network node, such as an evolved Node B, eNB, to a wire device, such as a user equipment, UE). An antenna port is generally used as a generic term for signal transmission under identical channel conditions. For each LTE operating mode in the downlink direction for which an independent channel is assumed, a separate logical antenna port is defined. LTE symbols that are transmitted via identical antenna ports are subject to the same channel conditions. In order to determine the characteristic channel for an antenna port, a UE must today carry out separate channel estimation for each antenna port. Separate reference signals (pilot signals) that are suitable for estimating the respective channel are defined in the LTE standard for each antenna port.
Further, coordinated multi-point transmission/reception (CoMP) is one concept that was first introduced in Release 10 of LTE. In CoMP, UEs can receive coordinated data transmissions from multiple sectors or cells. In CoMP scenarios, it may be advantageous to map transmitter (TX) antenna ports of the network node to geographically separated antennas at different transmission points (TPs) within a cell of the network node. Commonly there may be in the order of 1 to 8 antenna ports.
The way in which these logical antenna ports are assigned to the physical transmit antennas of a network node is up to the network node, and can vary between network nodes of the same type (because of different operating conditions) and also between network nodes from different manufacturers. The network node does not explicitly notify the UE of the mapping that has been carried out, rather the UE must today take this into account automatically during demodulation.
There is thus a need for an improved detection of transmit antenna ports at the UE.